Place the mint, parsley, garlic and Serrano chiles in a food processor and process until coarsely chopped. Add the mustard and process until combined. With the motor running, slowly add 1/2 cup of the olive oil until emulsified, adding a bit more if needed.

Transfer the mixture to a bowl and whisk in a few tablespoons of cold water to thin to a sauce-like consistency. Season with salt, pepper and honey (if needed) to taste. Reserve.

For the spice rub, whisk together the paprikas, coriander, mustard, fennel, pepper and salt in a small bowl. Season the chicken breasts on both sides with salt and pepper. Rub the top side of the chicken breasts with some of the spice rub.

Heat the oil in a large, nonstick saut pan over high heat until it begins to shimmer. Add the chicken, rub-side down and cook until golden brown and a crust forms, about 4 minutes. Turn the breasts over and continue cooking until just cooked through, 4-5 minutes. Transfer the chicken to a platter and drizzle with some of the Parsley-Mint Sauce. Let rest 5 minutes. Serve with additional sauce on the side.